1. Field of the Invention
The present invention relates to a lamination system for thermocompression bonding of laminate films, each having a heat adhesive layer, on top and/or back surfaces of ID cards or the like. More specifically, this invention relates to the lamination system provided with contact type temperature detection devices for detecting surface temperatures of heat rollers.
2. Description of the Prior Art
Recently, ID cards of various types are being widely used. In order to protect an ID card from tampering or to improve the life of the ID card, a transparent film of about 30 μm in thickness is laminated by a thermocompression bonding on a surface of the ID card on which information data are printed. Lamination systems such as disclosed in U.S. Pat. No. 5,807,461, U.S. Pat. No. 5,783,024 or U.S. Pat. No. 6,159,327 are known as systems suitable for such lamination.
In the lamination system disclosed in U.S. Pat. No. 5,807,461, a transparent film pre-cut in a predetermined shape (a patch) is mounted on a carrier (a base sheet). The carrier is provided with sensor marks (index markings) for detecting the position of the pre-cut patch on the carrier. The lamination system detects the sensor mark prior to the lamination to detect the position of the pre-cut patch, then tears the patch from the carrier and laminates the patch on a surface of a printed ID card by thermocompression bonding. Such lamination system is undesirable in view of the operational cost and the environmental protection, since the carrier is thrown away as a waste material.
In a lamination system disclosed in U.S. Pat. No. 5,783,024 in which the above mentioned problem is solved, a leading edge of a continuous transparent laminate film is drawn out from a supply roll, then transferred along a film transfer path, and then cut into a predetermined length. The cut laminate film is further transferred along the film transfer path to a convergence zone. On the other hand, a card to be laminated with the cut film is put into the lamination system, after being printed by a card printer. The card is also transferred along a card transfer path to the convergence zone. The cut laminate film is laid on the card at the convergence zone. The cut laminate film and the card are then transferred to a thermocompression bonding part, where they are bonded with each other by thermocompression bonding using a heat roller or heat rollers provided there.
Such lamination system is advantageous in view of the operational cost and the environmental protection, since the laminate film is used after being cut in a necessary length, and consequently, no waste carrier such as in the lamination system disclosed in U.S. Pat. No. 5,807,461 is left. So, such lamination system is called wasteless type lamination system.
Further, in U.S. Pat. No. 6,159,327, a lamination system for laminating both surfaces of a card using a pair of lamination systems similar to that disclosed in U.S. Pat. No. 5,807,461 is disclosed.
In these lamination systems, surface temperature of a heat roller needs to be controlled appropriately according to the material of a card to be laminated. At present, such surface temperature control is being made, in general, estimating the surface temperature based on temperature information obtained by a temperature detection device placed inside of the heat roller. However, for more accurate control of the surface temperature, it is desirable to directly measure the surface temperature. Direct measurement of the surface temperature can be done by a temperature detection device comprising a contact type temperature element, such as a thermistor for example, contacting slidably with the surface of the heat roller.
In the meantime, it sometimes happens that a heat roller in a lamination system is contaminated or damaged by a foreign substance such as a burr of a card edge for example. Consequently, a contaminated or damaged heat roller needs to be detached for cleaning, or it needs to be exchanged with another one in some cases.
However, in case that a temperature detection device is provided in contact with a surface of a heat roller, it is difficult to detach the heat roller from, or attach the heat roller to, the lamination system, with the temperature detection device in its installed position. Further, in case that the temperature detection device is detached each time when the heat roller is detached from, or attached to, the lamination system, the temperature detection device is liable to be damaged.